States

Toxic vapor cloud impacts from accidental releases of anhydrous ammonia and nitrogen dioxide at the ICPP NO{sub x} Abatement Facility (open access)

Toxic vapor cloud impacts from accidental releases of anhydrous ammonia and nitrogen dioxide at the ICPP NO{sub x} Abatement Facility

This report evaluates potential atmospheric and human health impacts that may result from accidental releases of anhydrous ammonia and nitrogen dioxide at the Idaho Chemical Processing Plant (ICPP) NO{sub x} Abatement Facility. Excess process gas releases are evaluated using a traditional Gaussian puff model. Dense two-phase aerosol releases from an 18,000 gallon liquefied ammonia storage tank and a 6,000 gallon tanker truck accident are evaluated using the refined vapor dispersion model, SLAB. The SLAB results are also compared to those using the neutral-buoyancy puff model. A SLAB sensitivity analysis is presented which examines various combinations of ambient temperatures and wind speeds in order to determine worst-case downwind air concentrations. The results from the storage tank releases indicated that potentially serious ammonia concentrations (greater than 1000 ppm) could result at downwind distances ranging from 150 meters (relief valve malfunction) to approximately 3 kilometers (catastrophic tank failure). The tank failure scenario produced concentrations that could be rapidly fatal (greater than 5000 ppm) out to 1.3 kilometers. Under worst-case meteorological dispersion conditions, recognized exposure limits (IDLH, TLV-STEL) were exceeded for very large distances (greater than 15 kilometers).
Date: April 1, 1992
Creator: Abbott, M. L.
Object Type: Report
System: The UNT Digital Library
Toxic vapor cloud impacts from accidental releases of anhydrous ammonia and nitrogen dioxide at the ICPP NO sub x Abatement Facility (open access)

Toxic vapor cloud impacts from accidental releases of anhydrous ammonia and nitrogen dioxide at the ICPP NO sub x Abatement Facility

This report evaluates potential atmospheric and human health impacts that may result from accidental releases of anhydrous ammonia and nitrogen dioxide at the Idaho Chemical Processing Plant (ICPP) NO{sub x} Abatement Facility. Excess process gas releases are evaluated using a traditional Gaussian puff model. Dense two-phase aerosol releases from an 18,000 gallon liquefied ammonia storage tank and a 6,000 gallon tanker truck accident are evaluated using the refined vapor dispersion model, SLAB. The SLAB results are also compared to those using the neutral-buoyancy puff model. A SLAB sensitivity analysis is presented which examines various combinations of ambient temperatures and wind speeds in order to determine worst-case downwind air concentrations. The results from the storage tank releases indicated that potentially serious ammonia concentrations (greater than 1000 ppm) could result at downwind distances ranging from 150 meters (relief valve malfunction) to approximately 3 kilometers (catastrophic tank failure). The tank failure scenario produced concentrations that could be rapidly fatal (greater than 5000 ppm) out to 1.3 kilometers. Under worst-case meteorological dispersion conditions, recognized exposure limits (IDLH, TLV-STEL) were exceeded for very large distances (greater than 15 kilometers).
Date: April 1, 1992
Creator: Abbott, M.L.
Object Type: Report
System: The UNT Digital Library
Analytical and experimental evaluation of joining ceramic oxides to ceramic oxides and ceramic oxides to metal for advanced heat engine applications (open access)

Analytical and experimental evaluation of joining ceramic oxides to ceramic oxides and ceramic oxides to metal for advanced heat engine applications

The problem of designing reliable, high strength zirconia-to-zirconia and zirconia-to-nodular cast iron joints is addressed by developing a general joint design and assessment methodology. A joint's load carrying capability is predicted in terms of its material strength and fracture toughness characteristics. The effects of joint constituent properties and joining process variables are included. The methodology is verified in a two step process by applying it first to notched bend bars and then to a notched disk specimen loaded in compression. Key technical accomplishments in the program include the development of a joint design and assessment methodology which predicts failure based on a combination of strength and toughness, the development of a new method of hot forging magnesia partially stabilized zirconia to itself, and the development of a bimaterial disk-shaped specimen notched along the diametral bond line and compressively loaded to generate both shear and tensile loadings on the bond line. Mechanical and thermal characterization of joints, adherents, and interlayer materials were performed to provide data for input to the design methodology. Results from over 150 room temperature tests and 30 high temperature tests are reported. Extensive comparisons of experimental results are made with model predictions of failure load. The joint …
Date: April 1, 1992
Creator: Ahmad, J.; Majumdar, B.; Rosenfield, A. R.; Swartz, S. L.; Cawley, J.; Park, E. et al.
Object Type: Report
System: The UNT Digital Library
Analytical and experimental evaluation of joining ceramic oxides to ceramic oxides and ceramic oxides to metal for advanced heat engine applications. Final report (open access)

Analytical and experimental evaluation of joining ceramic oxides to ceramic oxides and ceramic oxides to metal for advanced heat engine applications. Final report

The problem of designing reliable, high strength zirconia-to-zirconia and zirconia-to-nodular cast iron joints is addressed by developing a general joint design and assessment methodology. A joint`s load carrying capability is predicted in terms of its material strength and fracture toughness characteristics. The effects of joint constituent properties and joining process variables are included. The methodology is verified in a two step process by applying it first to notched bend bars and then to a notched disk specimen loaded in compression. Key technical accomplishments in the program include the development of a joint design and assessment methodology which predicts failure based on a combination of strength and toughness, the development of a new method of hot forging magnesia partially stabilized zirconia to itself, and the development of a bimaterial disk-shaped specimen notched along the diametral bond line and compressively loaded to generate both shear and tensile loadings on the bond line. Mechanical and thermal characterization of joints, adherents, and interlayer materials were performed to provide data for input to the design methodology. Results from over 150 room temperature tests and 30 high temperature tests are reported. Extensive comparisons of experimental results are made with model predictions of failure load. The joint …
Date: April 1, 1992
Creator: Ahmad, J.; Majumdar, B.; Rosenfield, A. R.; Swartz, S. L.; Cawley, J.; Park, E. et al.
Object Type: Report
System: The UNT Digital Library
Stress-Relief Displacements Induced by Drilling--Applications to Holographic Measurements of in Situ Stress (open access)

Stress-Relief Displacements Induced by Drilling--Applications to Holographic Measurements of in Situ Stress

The holographic stressmeter is an instrument which has been developed at Caltech to allow determination of the complete stress tensor from in situ borehole measurements. The stressmeter uses double-exposure holographic interferometry to record the displacements induced by the drilling of a small sidehole into the borehole wall. The local stresses, which are the result of the far-field stresses, concentrated at the borehole, cause deformation of the surface of the borehole wall in the vicinity of the sidehole. The first part of this study uses a thin infinite elastic plate subjected to plane stress at infinity to model the displacements at the borehole wall. However, the existence of some holograms which were difficult to model closely led us to examine the validity of this model. In order to investigate the problem further, we performed a two-dimensional finite element analysis for an elastic box with a terminated hole. We varied the dimensions of the hole to see what effect the radius and depth of the hole might have on the displacements. The plate model predicts that the depth of the hole should have no effect on the horizontal components of displacement, but the finite element results show that the magnitude of both …
Date: April 24, 1992
Creator: Ahrens, T. J. & Smither, C. L.
Object Type: Report
System: The UNT Digital Library
Stress-Relief Displacements Induced by Drilling--Applications to Holographic Measurements of in Situ Stress. Final Technical Report, August 15, 1988--August 14, 1990 (open access)

Stress-Relief Displacements Induced by Drilling--Applications to Holographic Measurements of in Situ Stress. Final Technical Report, August 15, 1988--August 14, 1990

The holographic stressmeter is an instrument which has been developed at Caltech to allow determination of the complete stress tensor from in situ borehole measurements. The stressmeter uses double-exposure holographic interferometry to record the displacements induced by the drilling of a small sidehole into the borehole wall. The local stresses, which are the result of the far-field stresses, concentrated at the borehole, cause deformation of the surface of the borehole wall in the vicinity of the sidehole. The first part of this study uses a thin infinite elastic plate subjected to plane stress at infinity to model the displacements at the borehole wall. However, the existence of some holograms which were difficult to model closely led us to examine the validity of this model. In order to investigate the problem further, we performed a two-dimensional finite element analysis for an elastic box with a terminated hole. We varied the dimensions of the hole to see what effect the radius and depth of the hole might have on the displacements. The plate model predicts that the depth of the hole should have no effect on the horizontal components of displacement, but the finite element results show that the magnitude of both …
Date: April 24, 1992
Creator: Ahrens, T. J. & Smither, C. L.
Object Type: Report
System: The UNT Digital Library
Effect of metallic coating properties on the tribology of oil- lubricated coated-ceramics (open access)

Effect of metallic coating properties on the tribology of oil- lubricated coated-ceramics

The friction and wear behavior of zirconia ceramics lubricated with solid coatings (AG, Au, and Nb), deposited by ion-beam-assisted-deposition (IBAD) techniques, and a polyol-ester-based synthetic oil are presented. These results demonstrate that, although the simultaneous use of soft (e.g. Ag and Au) solid lubricants in conjunction with the synthetic lubricant significantly reduces the friction and wear under boundary lubrication at temperatures up to 250{degree}C, the durability of the soft films was poor. In contrast, durability of Nb coating (in terms of chemical reactivity and adhesion during the tribo-tests) was better than that of the Ag or Au films. However, the friction and wear behavior of the Nb-coated films was poorer than that of the ceramics coated with Ag or Au.
Date: April 1, 1992
Creator: Ajayi, O. O.; Fenske, G. R.; Erdemir, A.; Erck, R. A.; Hsieh, J. H. & Nichols, F. A.
Object Type: Article
System: The UNT Digital Library
Module process optimization and device efficiency improvement for stable, low-cost, large-area, cadmium telluride-based photovoltaic module production (open access)

Module process optimization and device efficiency improvement for stable, low-cost, large-area, cadmium telluride-based photovoltaic module production

This report describes work under a three-year phased subcontract to develop CdS/CdTe devices and modules and to further improve the technology base at Photon Energy, Inc. (PEI) to better address the commercialization issues and objectives of the PEI and the US Department of Energy. During this reporting period we (1) achieved efficiencies of 12.7% on small area devices, (2) achieved 1-ft{sup 2} modules with over 8% aperture-area efficiency (and active area efficiencies up to {approximately}10%), (3) tested 4-ft{sup 2} modules at NREL at 23.1 (21.3) watts, normalized (6.3% efficiency), and (4) found no inherent stability problems with CdTe technology during life testing, at both NREL and PEI. 7 refs.
Date: April 1, 1992
Creator: Albright, S. P.; Ackerman, B.; Chamberlin, R. R. & Jordan, J. F.
Object Type: Report
System: The UNT Digital Library
Module process optimization and device efficiency improvement for stable, low-cost, large-area, cadmium telluride-based photovoltaic module production. Annual subcontract report, 1 July 1990--31 December 1991 (open access)

Module process optimization and device efficiency improvement for stable, low-cost, large-area, cadmium telluride-based photovoltaic module production. Annual subcontract report, 1 July 1990--31 December 1991

This report describes work under a three-year phased subcontract to develop CdS/CdTe devices and modules and to further improve the technology base at Photon Energy, Inc. (PEI) to better address the commercialization issues and objectives of the PEI and the US Department of Energy. During this reporting period we (1) achieved efficiencies of 12.7% on small area devices, (2) achieved 1-ft{sup 2} modules with over 8% aperture-area efficiency (and active area efficiencies up to {approximately}10%), (3) tested 4-ft{sup 2} modules at NREL at 23.1 (21.3) watts, normalized (6.3% efficiency), and (4) found no inherent stability problems with CdTe technology during life testing, at both NREL and PEI. 7 refs.
Date: April 1, 1992
Creator: Albright, S. P.; Ackerman, B.; Chamberlin, R. R. & Jordan, J. F.
Object Type: Report
System: The UNT Digital Library
Physical mechanisms contributing to the episodic gas release from Hanford tank 241-SY-101 (open access)

Physical mechanisms contributing to the episodic gas release from Hanford tank 241-SY-101

Volume growth of contents in a waste storage tank at Hanford is accompanied by episodic releases of gas and a rise in the level of tank contents. A theory is presented to describe how the gas is retained in the waste and how it is released. The theory postulates that somewhat cohesive gobs of sludge rise from the lower regions of the tank and buoyancy overcomes the cohesive strength of the slurry; this quantitatively explains several of the measured phenomena and qualitatively explains other observations.
Date: April 1, 1992
Creator: Allemann, R. T.
Object Type: Article
System: The UNT Digital Library
Physical mechanisms contributing to the episodic gas release from Hanford tank 241-SY-101 (open access)

Physical mechanisms contributing to the episodic gas release from Hanford tank 241-SY-101

Volume growth of contents in a waste storage tank at Hanford is accompanied by episodic releases of gas and a rise in the level of tank contents. A theory is presented to describe how the gas is retained in the waste and how it is released. The theory postulates that somewhat cohesive gobs of sludge rise from the lower regions of the tank and buoyancy overcomes the cohesive strength of the slurry; this quantitatively explains several of the measured phenomena and qualitatively explains other observations.
Date: April 1, 1992
Creator: Allemann, R.T.
Object Type: Article
System: The UNT Digital Library
Environmental amenities and the location of industrial activity (open access)

Environmental amenities and the location of industrial activity

Discussion of the impacts of perceived risk on decisions to locate business activity in areas likely to host noxious facilities has become an important part of socioeconomic impact analysis. The paper reviews the literature and presents empirical evidence, and shows that amenities are only a significant location factor for certain types of business activity. Policies to offset the potential loss of businesses through perceived risk in communities hosting waste facilities, should, therefore, carefully consider the sensitivity to environmental amenities of the types of business activity present or likely to locate.
Date: April 1, 1992
Creator: Allison, T. & Calzonetti, F.
Object Type: Article
System: The UNT Digital Library
Particle production models in HETC88 in the energy range 3 to 30 GeV (open access)

Particle production models in HETC88 in the energy range 3 to 30 GeV

HETC88 is the latest version of the high-energy transport code HETC that has been used to provide accelerator shield and calorimeter design data for many years. (See Refs. 3, 4, and 5 and the refs. given therein). This version of the code is described and results are compared with experimental data in Ref. 1. The high-energy particle production model in HETC88 is a multi-chain fragmentation model based on the work of J. Ranft and S. Ritter (see Ref. 6 and the refs. given therein). The fragmentation model used in HETC88 is described and compared with experimental data. In HETC88, the fragmentation model is used at energies {ge} 5 GeV, a scaling model is used in energy range 3 to 5 GeV, and the intranuclear cascade model is used at energies {le} 3 GeV. 10 refs., 1 fig.
Date: April 1992
Creator: Alsmiller, R. G., Jr. & Alsmiller, F. S.
Object Type: Article
System: The UNT Digital Library
Innovative technology demonstrations (open access)

Innovative technology demonstrations

Currently, several innovative technologies are being demonstrated at Tinker Air Force Base (TAFB) to address specific problems associated with remediating two contaminated test sites at the base. Cone penetrometer testing (CPT) is a form of testing that can rapidly characterize a site. This technology was selected to evaluate its applicability in the tight clay soils and consolidated sandstone sediments found at TAFB. Directionally drilled horizontal wells have been successfully installed at the US Department of Energy`s (DOE) Savannah River Site to test new methods of in situ remediation of soils and ground water. This emerging technology was selected as a method that may be effective in accessing contamination beneath Building 3001 without disrupting the mission of the building, and in enhancing the extraction of contamination both in ground water and in soil. A soil gas extraction (SGE) demonstration, also known as soil vapor extraction, will evaluate the effectiveness of SGE in remediating fuels and TCE contamination contained in the tight clay soil formations surrounding the abandoned underground fuel storage vault located at the SW Tanks Site. In situ sensors have recently received much acclaim as a technology that can be effective in remediating hazardous waste sites. Sensors can be useful …
Date: April 1, 1992
Creator: Anderson, D. B.; Hartley, J. N. & Luttrell, S. P.
Object Type: Report
System: The UNT Digital Library
Innovative technology demonstration (open access)

Innovative technology demonstration

The Innovative Technology Demonstration (ITD) program at Tinker Air Force Base (TAFB), Oklahoma City, Oklahoma, will demonstrate the overall utility and effectiveness of innovative technologies for site characterization, monitoring, and remediation of selected contaminated test sites. The current demonstration test sites include a CERCLA site on the NPL list, located under a building (Building 3001) that houses a large active industrial complex used for rebuilding military aircraft, and a site beneath and surrounding an abandoned underground tank vault used for storage of jet fuels and solvents. The site under Building 3001 (the NW Test Site) is contaminated with TCE and Cr{sup {plus}6}; the site with the fuel storage vault (the SW Tanks Site) is contaminated with fuels, BTEX and TCE. These sites and others have been identified for cleanup under the Air Force`s Installation Restoration Program (IRP). This document describes the demonstrations that have been conducted or are planned for the TAFB.
Date: April 1, 1992
Creator: Anderson, D. B.; Luttrell, S. P.; Hartley, J. N. & Hinchee, R.
Object Type: Article
System: The UNT Digital Library
Innovative technology demonstrations (open access)

Innovative technology demonstrations

Currently, several innovative technologies are being demonstrated at Tinker Air Force Base (TAFB) to address specific problems associated with remediating two contaminated test sites at the base. Cone penetrometer testing (CPT) is a form of testing that can rapidly characterize a site. This technology was selected to evaluate its applicability in the tight clay soils and consolidated sandstone sediments found at TAFB. Directionally drilled horizontal wells have been successfully installed at the US Department of Energy's (DOE) Savannah River Site to test new methods of in situ remediation of soils and ground water. This emerging technology was selected as a method that may be effective in accessing contamination beneath Building 3001 without disrupting the mission of the building, and in enhancing the extraction of contamination both in ground water and in soil. A soil gas extraction (SGE) demonstration, also known as soil vapor extraction, will evaluate the effectiveness of SGE in remediating fuels and TCE contamination contained in the tight clay soil formations surrounding the abandoned underground fuel storage vault located at the SW Tanks Site. In situ sensors have recently received much acclaim as a technology that can be effective in remediating hazardous waste sites. Sensors can be useful …
Date: April 1, 1992
Creator: Anderson, D.B.; Hartley, J.N. & Luttrell, S.P.
Object Type: Report
System: The UNT Digital Library
Innovative technology demonstration (open access)

Innovative technology demonstration

The Innovative Technology Demonstration (ITD) program at Tinker Air Force Base (TAFB), Oklahoma City, Oklahoma, will demonstrate the overall utility and effectiveness of innovative technologies for site characterization, monitoring, and remediation of selected contaminated test sites. The current demonstration test sites include a CERCLA site on the NPL list, located under a building (Building 3001) that houses a large active industrial complex used for rebuilding military aircraft, and a site beneath and surrounding an abandoned underground tank vault used for storage of jet fuels and solvents. The site under Building 3001 (the NW Test Site) is contaminated with TCE and Cr{sup {plus}6}; the site with the fuel storage vault (the SW Tanks Site) is contaminated with fuels, BTEX and TCE. These sites and others have been identified for cleanup under the Air Force's Installation Restoration Program (IRP). This document describes the demonstrations that have been conducted or are planned for the TAFB.
Date: April 1, 1992
Creator: Anderson, D.B.; Luttrell, S.P. (Pacific Northwest Lab., Richland, WA (United States)); Hartley, J.N. (Battelle Environmental Management Operations, Richland, WA (United States)) & Hinchee, R. (Battelle, Columbus, OH (United States))
Object Type: Article
System: The UNT Digital Library
Radioactive demonstration of DWPF product control strategy (open access)

Radioactive demonstration of DWPF product control strategy

The effectiveness of the product and process control strategies that will be utilized by the Defense Waste Processing Facility (DWPF) was demonstrated during a campaign in the Shielded Cells Facility (SCF) of the Savannah River Technology Center (SRTC). The remotely operated process included the preparation of the melter feed, vitrification in a slurry-fed 1/100th scale melter and analysis of the glass product both for its composition and durability. The campaign processed approximately 10 kg (on a dry basis) of radioactive sludge from Tank 51. This sludge is representative of the first batch of sludge that will be sent to the DWPF for immobilization into borosilicate glass. Additions to the sludge were made based on calculations using the Product Composition Control System (PCCS). Analysis of the glass produced during the campaign showed that a durable glass was produced with a composition similar to that predicted using the PCCS.
Date: April 22, 1992
Creator: Andrews, M. K. & Bibler, N. E.
Object Type: Report
System: The UNT Digital Library
Radioactive demonstration of DWPF product control strategy (open access)

Radioactive demonstration of DWPF product control strategy

The effectiveness of the product and process control strategies that will be utilized by the Defense Waste Processing Facility (DWPF) was demonstrated during a campaign in the Shielded Cells Facility (SCF) of the Savannah River Technology Center (SRTC). The remotely operated process included the preparation of the melter feed, vitrification in a slurry-fed 1/100th scale melter and analysis of the glass product both for its composition and durability. The campaign processed approximately 10 kg (on a dry basis) of radioactive sludge from Tank 51. This sludge is representative of the first batch of sludge that will be sent to the DWPF for immobilization into borosilicate glass. Additions to the sludge were made based on calculations using the Product Composition Control System (PCCS). Analysis of the glass produced during the campaign showed that a durable glass was produced with a composition similar to that predicted using the PCCS.
Date: April 22, 1992
Creator: Andrews, M. K. & Bibler, N. E.
Object Type: Report
System: The UNT Digital Library
Combustion of dense streams of coal particles (open access)

Combustion of dense streams of coal particles

Research on coal combustion continued. Activities during November 29, 1991 to February 28, 1992 includes: Further analytical results on char array combustion and internal ignition of porous char; preliminary runs using a flat flame burner have been made and a blue flat flame has been obtained; a CID camera, EPIX frame grabber and software, Sony monitor and a 486 Computer to handle image processing frame by frame have been acquired; a new coal feeder has been constructed for feeding through the flat flame burner. Coal experiments have not yet been conducted. Coal samples from Penn State Coal Bank were also acquired for use in the experiments. They include bituminous and subbituminous coals of differing VM.
Date: April 14, 1992
Creator: Annamalai, K.
Object Type: Report
System: The UNT Digital Library
Combustion of dense streams of coal particles. Quarterly progress report No. 6, November 29, 1991--February 28, 1992 (open access)

Combustion of dense streams of coal particles. Quarterly progress report No. 6, November 29, 1991--February 28, 1992

Research on coal combustion continued. Activities during November 29, 1991 to February 28, 1992 includes: Further analytical results on char array combustion and internal ignition of porous char; preliminary runs using a flat flame burner have been made and a blue flat flame has been obtained; a CID camera, EPIX frame grabber and software, Sony monitor and a 486 Computer to handle image processing frame by frame have been acquired; a new coal feeder has been constructed for feeding through the flat flame burner. Coal experiments have not yet been conducted. Coal samples from Penn State Coal Bank were also acquired for use in the experiments. They include bituminous and subbituminous coals of differing VM.
Date: April 14, 1992
Creator: Annamalai, K.
Object Type: Report
System: The UNT Digital Library
Influence of Prandtl number and effects of disruption shape on the performance of enhanced tubes with the separation and reattachment mechanism (open access)

Influence of Prandtl number and effects of disruption shape on the performance of enhanced tubes with the separation and reattachment mechanism

The pressure-drop and heat-transfer performance of an enhanced tube with transverse disruptions can be predicted with a numerical modeling method, an accomplishment not previously achieved. Two computer codes were employed to achieve this goal - an orthogonal code and a nonorthogonal, body-fitted code. The turbulence closure was achieved with a two-layer turbulence model. The orthogonal computer code was used to determine the influence of the Prandti number. The numerical simulations demonstrated that six distinct regions exist and that three zones dominate the thermal performance. The nonorthogonal, body-fitted numerical code was used to determine the thermohydraulic performance of enhanced tubes with transverse, periodic sine-, semicircle-, arc-, and trapezoid-shaped disruptions. The research showed that there was a trade-off between the heat-transfer and pressure-drop performances when the disruption shape becomes more contoured, and that the local heat transfer is strongly dependent on the shape in the vicinity of the disruption, but it is less dependent in the downstream recirculation region and in the boundary-layer development zone.
Date: April 1, 1992
Creator: Arman, B. & Rabas, T. J.
Object Type: Report
System: The UNT Digital Library
Influence of Prandtl number and effects of disruption shape on the performance of enhanced tubes with the separation and reattachment mechanism (open access)

Influence of Prandtl number and effects of disruption shape on the performance of enhanced tubes with the separation and reattachment mechanism

The pressure-drop and heat-transfer performance of an enhanced tube with transverse disruptions can be predicted with a numerical modeling method, an accomplishment not previously achieved. Two computer codes were employed to achieve this goal - an orthogonal code and a nonorthogonal, body-fitted code. The turbulence closure was achieved with a two-layer turbulence model. The orthogonal computer code was used to determine the influence of the Prandti number. The numerical simulations demonstrated that six distinct regions exist and that three zones dominate the thermal performance. The nonorthogonal, body-fitted numerical code was used to determine the thermohydraulic performance of enhanced tubes with transverse, periodic sine-, semicircle-, arc-, and trapezoid-shaped disruptions. The research showed that there was a trade-off between the heat-transfer and pressure-drop performances when the disruption shape becomes more contoured, and that the local heat transfer is strongly dependent on the shape in the vicinity of the disruption, but it is less dependent in the downstream recirculation region and in the boundary-layer development zone.
Date: April 1, 1992
Creator: Arman, B. & Rabas, T. J.
Object Type: Report
System: The UNT Digital Library
Growth of II-VI thin-films from single-source precursors based on sterically encumbered sitel ligands (open access)

Growth of II-VI thin-films from single-source precursors based on sterically encumbered sitel ligands

We have developed a new route to MOCVD of II-VI compounds based on the use of novel single-source precursors in which the II-VI elements are combined at the molecular level in a single covalent compound. We have prepared and fully characterized a number of new derivatives of zinc, cadmium and mercury incorporating large, sterically demanding tellurolate ligands of general formula: M(sitel){sub 2} where sitel = -TeSi(SiMe{sub 3}){sub 3}. The crystalline compounds are relatively volatile and are easily manipulated under nitrogen. Several of these compounds have been tested for their suitability as precursors in the MOCVD process. Clean pyrolysis reactions and deposition of thin films were achieved. The stoichiometry of the pyrolysis reaction has been determined by analysis of the reaction by-products.
Date: April 1, 1992
Creator: Arnold, J.; Seligson, A. L.; Walker, J. M.; Bourret, E. D. & Bonasia, P. J.
Object Type: Article
System: The UNT Digital Library